The present application claims priority under 35 U.S.C. xc2xa7119 to Korean Application No. 2000-28973, which is hereby incorporated by reference in its entirety for all purposes.
1. Field of the Invention
The present invention relates to a fire alarm apparatus, and more particularly to an apparatus and a method for monitoring line disconnection and occurrence of fire, capable of checking line disconnection and occurrence of fire regardless of the installation place of a terminal endpoint resistor that is for monitoring disconnection of the line connected to a fire detector, and a fire alarm apparatus having the same.
2. Description of the Related Art
In general, in high and large buildings like offices and factories where many people come in and out, it is obligatory to install a fire alarm apparatus to minimize life injury by a fire. FIG. 1 shows a line-wiring state of a conventional fire alarm apparatus in which a fire detector directly detects fire. Referring to FIG. 1, a plurality of fire detectors 3, 4 and 5 for detecting a fire are installed between a repeater 1 and a transmitter 2. Lines of the plurality of fire detectors 3, 4 and 5 are mutually wired between the repeater 1 and the transmitter 2 to be electrically connected with one another.
When the plurality of fire detectors 3, 4 and 5 detect a fire, a fire detecting signal for informing occurrence of fire is provided from the fire detector which detects the fire, to the repeater 1. Repeater 1 informs a control center of the occurrence of fire through a fire receiver (not shown). In the above-mentioned fire alarm apparatus, the number of the plurality of the fire detectors 3, 4 and 5 will be greatly increased in accordance with the size of the building in which it is installed, and the length of the line which electrically connects the plurality of the fire detectors 3, 4 and 5 will also be increased in proportion to the area in which it is installed.
In general, in a fire alarm apparatus, terminal endpoint resistors 6 and 7 are installed, as shown in the FIG. 1, to check for a disconnection of the line of the fire detector, which is very long as described above. The terminal endpoint resistors 6 and 7 have to be installed at an end portion of the line, that is, at the reference mark xe2x80x9cBxe2x80x9d in FIG. 1. However, an equipment provider that installs a fire alarm apparatus may install the terminal endpoint resistor 6 at a center portion of the line; that is to say, at the reference mark xe2x80x9cAxe2x80x9d in FIG. 1, to avoid the trouble of maintenance and repair caused by line disconnection. When the terminal endpoint resistor 6 is installed in this way, at the position of the repeater 1, the line is detected as normal even though the line between installation place A of the terminal endpoint resistor 6 and the transmitter 2 is disconnected at reference mark xe2x80x9cCxe2x80x9d, for instance. Therefore, the fire detectors 4 and 5 installed between the installation place A and the transmitter 2 are not able to detect a fire, and the fire alarm apparatus can not generate a fire alarm.
U.S. Pat. No. 5,086,293 (granted to Karou Takahashi et al.) titled xe2x80x9cLINE INTERRUPTION SUPERVISORY DEVICE FOR A FIRE ALARM SYSTEMxe2x80x9d discloses a line interruption supervising apparatus for a fire alarm system that is capable of monitoring a line state regardless of the line length and the number of fire detectors. According to the aforementioned apparatus, a voltage level of the power/signal lines before the power supply interruption is compared with a line voltage level after a lapse of a predetermined time from the power supply interruption, and the open/interruption state of the power/signal line for fire detecting is determined based on the compared result.
Also, U.S. Pat. No. 4,568,923 (granted to Hiroshi Ouchi) discloses a fire alarm system that is capable of detecting line disconnection of the alarm line, wherein the fire detectors are installed without discontinuing the fire detecting function.
However, according to the aforementioned conventional apparatuses, the systems are not capable of precisely checking the line disconnection state with respect to the installation place of the terminal endpoint resistors, and are not capable of controlling the fire alarm preferably with respect to the respective states of line disconnection and fire. Moreover, when a fire occurs, an indicating lamp mounted on transmitter 2 of FIG. 1 for example, is set to be continuously turned-on, so that it is difficult to locate the place of an in-house fireplug when a great deal of smoke is present.
The present invention is therefore directed an apparatus and method for monitoring line disconnection and occurrence of fire, which substantially overcomes one or more of the problems due to the limitations and disadvantages of the prior art.
Therefore, it is an object of the present invention to provide an apparatus and method for monitoring line disconnection and occurrence of fire, capable of checking line disconnection of the fire detector or occurrence of a fire regardless of the installation place of a terminal endpoint resistor that is installed for the purpose of checking disconnection of the line connected to a fire detector.
It is another object of the present invention to provide an apparatus and method that enable easy locating of an in-house fireplug.
It is still another object of the present invention to provide a fire alarm apparatus having an apparatus for monitoring line disconnection and occurrence of fire, capable of checking line disconnection of the fire detector or occurrence of a fire, regardless of the installation place of a terminal endpoint resistor that is installed for the purpose of checking disconnection of the line connected to the fire detector, while enabling an in-house fireplug to be easily located.
To achieve the aforementioned objects of the present invention, an apparatus for monitoring line disconnection and occurrence of fire according to a first embodiment of the present invention includes an operation verifier that outputs a first detecting voltage signal representing an operation state of a fire detector and that outputs a verification-confirming signal in response to a line disconnection-verifying signal, a first detector that outputs first and a second detecting signals respectively representing an operation state of the fire detector and a state of a first line of the fire detector in response to the first detecting voltage signal and the verification-confirming signal, and a second detector that receives a second detecting voltage signal representing the operation state of the fire detector to output a third detecting signal representing a state of a second line of the fire detector. Also, a controller receives the first, second and third detecting signals, compares a voltage level of the first detecting signal with a voltage level of a predetermined first reference value, provides the line disconnection-verifying signal to the operation verifier according to a compared result, based on the second detecting signal generated in accordance with a result of providing the line disconnection-verifying signal, generates either a first line disconnection control signal to inform a first line disconnection of the fire detector or a fire control signal to inform occurrence of fire, based on a comparison result of the voltage level of the third detecting signal with a voltage level of a predetermined second reference value, and generates a second line disconnection control signal to inform a second line disconnection of the fire detector.
An apparatus for monitoring line disconnection and occurrence of fire according to a second embodiment of the present invention, to achieve the above objects of the present invention, includes a plurality of detectors that detect occurrence of fire to output a fire occurring signal and a controller that receives a detecting voltage signal representing a present voltage state of the plurality of detectors through a line, compares a voltage level of the detecting voltage signal with a predetermined reference voltage level, and based on the compared result, generates either a line disconnection control signal or a fire control signal respectively representing disconnection of the line of the plurality of detectors or the occurrence of fire. In addition, a first alarm unit informs an operator of the disconnection of the line of the plurality of detectors in response to the line disconnection control signal, and a second alarm unit informs the operator of the occurrence of fire in response to the fire control signal.
To achieve the above objects of the present invention, the present invention provides a method for monitoring line disconnection and occurrence of fire in a fire alarm system, which includes comparing whether or not a voltage level of a first detecting signal representing a present voltage state of a fire detector is lower than a voltage level of a predetermined first reference value, generating a first line disconnection-verifying signal having a voltage value of high level and a second line disconnection-verifying signal having a voltage value of low level when the voltage level of the first detecting signal is lower than the voltage level of the predetermined first reference value and generating a line disconnection control signal representing line disconnection of the fire detector when a voltage level of a second detecting signal fed back through the line of the fire detector is respectively detected as a voltage level opposite to the voltage level of the first and the second line disconnection-verifying signals, and generating a fire control signal representing occurrence of fire regardless of the voltage level of the first and the second line disconnection-verifying signals when the voltage level of the second detecting signal fed back through the line of the fire detector is detected as a uniform voltage level.
In the above-mentioned apparatus of the first embodiment, the line disconnection-verifying signal is alternatively provided as a voltage signal of low level or as a voltage signal of high level corresponding to a predetermined period. Also, in the above mentioned apparatus of the second embodiment, the second alarm unit provides an alarm indicative of the occurrence of fire and the place thereof, by means of executing an on-and-off flashing operation to emit light.
According to the aforementioned fire alarm apparatus, the voltage level of a plurality of fire detectors in normal times is compared with a predetermined operation voltage level of the plurality of the fire detectors, which is set as a reference voltage level by a control section. In accordance with the compared result, the controller generates the line disconnection-verifying signal to receive the detecting signal representing the line state of a common line and a detecting line which are electrically connected to the plurality of fire detectors. Also, by means of comparing the detecting signal with another predetermined reference voltage level, the controller judges whether the detecting line and the common line are disconnected or whether a fire has occurred. The controller generates a line disconnection control signal or a fire control signal to control the fire alarm system according to the judged result.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.